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  • 1
    Electronic Resource
    Electronic Resource
    Malignant melanoma metastasis to brain: role of degradative enzymes and responses to paracrine growth factors (1993)
    Springer
    Journal of neuro-oncology 18 (1993), S. 139-149 
    Details
    ISSN: 1573-7373
    Keywords: melanoma ; metastasis ; proteases ; endoglycosidases ; growth factors ; growth factor receptors ; basement membrane ; blood brain barrier ; neurotrophins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Mouse and human melanoma cells metastatic to the brain express degradative enzyme activities that are used for invasion of brain basement membrane and parenchyma. Compared to poorly metastatic or lung- or ovary-metastatic murine melanoma lines, the brain-metastatic sublines secreted higher levels of a variety of degradative enzymes. Brain-metastatic murine and human melanoma cells also degraded subendothelial basement membrane and reconstituted basement membrane at rates higher than other metastatic melanoma cells. In some cases these degradative activities in mouse and human melanoma cells can be induced by paracrine factors known to be present in the brain parenchyma, such as nerve growth factor (NGF). NGF stimulates the expression of degradative enzymes, such as the endo-Β-glucuronidase heparanase, that are important in basement membrane penetration but this factor does not stimulate melanoma cell growth. The growth of brain-metastasizing melanoma cells appears to be stimulated by other paracrine growth factors, such as paracrine transferrin. Melanoma cells metastatic to brain express higher numbers of transferrin receptors and respond and proliferate at lower concentrations of transferrin than do melanoma cells metastatic to other sites or poorly metastatic melanoma cells. The results suggest that degradation and invasion of brain basement membrane and responses to paracrine neurotrophins and paracrine transferrins are important properties in brain metastasis of murine and human malignant melanoma cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01050420
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  • 2
    Electronic Resource
    Electronic Resource
    Dispersal-limited zooplankton distribution and community composition in new ponds (1995)
    Springer
    Hydrobiologia 313-314 (1995), S. 15-20 
    Details
    ISSN: 1573-5117
    Keywords: colonization ; rotifers ; zooplankton ; vagility ; dispersal ; metapopulations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Twelve new experimental ponds were constructed identically, filled simultaneously, had similar physical and chemical properties, and were maintained with minimal manipulation. Colonizing zooplankton communities were sampled bi-weekly for one year. Rotifers dominated zooplankton communities in densities, biomass, and species number (47 of 61 observed species were rotifers). Only 14 species were observed in all 12 ponds; 9 were rotifers. Twenty-nine species (26 rotifers) were recorded in 〈-6 ponds. Species with high vagility exhibited greater viability. Ponds differed in zooplankton community composition throughout the year, due to differences in both vagility and viability among colonizing species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00025926
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Modelling Spatio-Temporal Effects of Environment on Atlantic Herring, Clupea harengus (2000)
    Springer
    Environmental biology of fishes 58 (2000), S. 157-172 
    Details
    ISSN: 1573-5133
    Keywords: generalized additive models ; acoustics ; pelagic ; oceanography ; zooplankton ; North Sea ; abundance ; distribution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Trends in mean abundance of North Sea Atlantic herring, Clupea harengus, over the period of 1992–1995, were modelled as a function of spatial location and ocean environmental conditions using generalized additive models (GAM). In all four years, the average herring abundance was found to be highest in latitudes around 60.5°N, and decreased with increasing latitude. The thermocline depth had a significant effect on prespawning herring abundance both directly, as a main effect, and indirectly, through its interactive effect with the temperature at 60 m. Average herring abundance was highest in areas having deeper thermocline depths (up to 45 m) and temperatures at 60 m between 9 and 11°C. Prespawning herring abundance was greater in areas of cooler surface waters in the south than in the north. Well-mixed waters and transition zones between frontal and stratified areas having sea surface temperatures mainly between 11 and 12°C and to a lesser extent between 13 and 14°C were associated with the highest herring abundance. Herring appeared to avoid the cold bottom waters in summer. Multiyear GAM analysis revealed consistent environmental preferenda of herring and affirmed further a significant decrease in herring abundance. As herring numbers declined, the population aggregated in the most preferred areas. The inter-relationships of herring and environmental factors across the study period, were similar in their structure and significance, suggesting that preferred areas for location of herring can be reasonably predicted.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007693732571
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  • 4
    Electronic Resource
    Electronic Resource
    The role of trophic factors and autocrine/paracrine growth factors in brain metastasis (1995)
    Springer
    Clinical & experimental metastasis 13 (1995), S. 67-88 
    Details
    ISSN: 1573-7276
    Keywords: brain metastasis ; growth factors ; melanoma ; melanotropins ; nerve growth factor ; neurotrophins ; signal transduction ; tumor progression ; tyrosine receptor kinase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: The brain is a unique microenvironment enclosed by the skull, lacking lymphatic drainage and maintaining i highly regulated vascular transport barrier. To metastasize to the brain malignant tumor cells must attach to microvessel endothelial cells, respond to brain-derived invasion factors, invade the blood-brain barrier and respond to survival and growth factors. Trophic factors are important in brain invasion because they can act to stimulate this process. In responsive malignant cells trophic factors such as neurotrophins can promote invasion by enhancing the production of basement membrane-degradative enzymes (such as type IV collagenase/gelatinase and heparanase) capable of locally destroying the basement membrane and the blood-brain barrier. We examined human melanoma cell lines that exhibit varying abilities to form brain metastases. These melanoma lines express low-affinity neurotrophin receptor p75NTR in relation to their brain-metastatic potentials but the variants do not express trkA, the gene encoding a high affinity nerve growth factor (NGF) tyrosine kinase receptor p140 trkA . Melanoma cells metastatic to brain also respond to paracrine factors made by brain cells. We have found that a paracrine form of transferrin is important in brain metastasis, and brain-metastatic cells respond to low levels of transferrin and express high levels of transferrin receptors. Brain-metastatic tumor cells can also produce autocrine factors any inhibitors that influence their growth, invasion and survival in the brain. We found that brain-metastatic melanoma cells synthesize transcripts for the following autocrine growth factors: TGFβ, bFGF, TGFα and IL-1β. Synthesis of these factors may influence the production of neurotrophins by adjacent brain cells, such as oligodendrocytes and astrocytes. Increased amounts of NGF were found in tumor-adjacent tissues at the invasion front of human melanoma tumors in brain biopsies. Trophic factors, autocrine growth factors, paracrine growth factors and other factors may determine whether metastatic cells can successfully invade, colonize and grow in the central nervous system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00133612
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  • 5
    Electronic Resource
    Electronic Resource
    Trophic factors and central nervous system metastasis (1995)
    Springer
    Cancer and metastasis reviews 14 (1995), S. 303-321 
    Details
    ISSN: 1573-7233
    Keywords: brain metastasis ; melanoma ; tumor progression ; growth factors ; neurotrophins ; nerve growth factor ; melanotropins ; signal transduction ; tyrosine receptor kinase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract To metastasize to the central nervous system (CNS) malignant cells must attach to brain microvessel endothelial cells, respond to brain endothelial cell-derived motility factors, respond to CNS-derived invasion factors and invade the blood-brain barrier (BBB), and finally, respond to CNS survival and growth factors. Trophic factors such as the neurotrophins play an important role in tumor cell invasion into the CNS and in the survival of small numbers of malignant cells under stress conditions. Trophic factors promote BBB invasion by enhancing the production of basement membrane-degrading enzymes in neurotrophin-responsive cells. The expression of certain neurotrophin receptors on brain-metastasic neuroendrocrine cells occurs in relation to their invasive and survival properties. For example, CNS-metastatic melanoma cells respond to particular neurotrophins (nerve growth factor, neurotrophin-2) that can be secreted by normal cells within the CNS. In addition, a paracrine form of transferrin is important in CNS metastasis, and brain-metastatic cells respond to low levels of transferrin and express high levels of transferrin receptors. CNS-metastatic tumor cells can also produce autocrine factors and inhibitors that influence their growth, invasion and survival in the brain. Synthesis of paracrine factors and cytokines may influence the production of trophic factors by normal brain cells adjacent to tumor cells. Moreover, we found increased amounts of neurotrophins in brain tissue at the invasion front of human melanoma tumors in CNS biopsies. Thus the ability to form metastatic colonies in the CNS is dependent on tumor cell responses to trophic factors as well as autocrine and paracrine growth factors and probably other underdescribed factors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00690600
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  • 6
    Electronic Resource
    Electronic Resource
    Zooplankton may not disperse readily in wind, rain, or waterfowl (1998)
    Springer
    Hydrobiologia 287-388 (1998), S. 15-21 
    Details
    ISSN: 1573-5117
    Keywords: Rotifera ; zooplankton ; dispersal ; colonization ; wind ; rain ; waterfowl
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Zooplankton, and especially rotifers, have long been thought to be readily dispersed by wind, rain and animals (especially waterfowl). Given that premise, local processes (tolerance to abiotic conditions, biotic interactions) have been the main focus of ecological studies. We tested the premise of high dispersal rates by incubating particulates collected with windsocks and rain samplers at two sites over 1 year. The sites were 80 km apart and differed in proximity to water and surrounding terrain. We also incubated fecal material of wild ducks. Pond sediments were identically incubated as a test of incubation method. Only bdelloid rotifers were collected in wind samples, and only four rotifer species were collected in rain samples: Lecane leontina, Lecane closterocerca, Keratella cochlearis, and a bdelloid. No metazoans were found in incubated duck feces, yet incubated pond sediments yielded 11 rotifer, one copepod, four cladoceran, and three ostracod species. Our results do not support the premise of readily dispersed zooplankton. If zooplankton dispersal is infrequent and limited to few species, a series of other questions should be addressed on processes regulating zooplankton population dynamics and community composition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1017080029317
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    Paper (German National Licenses)
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  • 7
    Electronic Resource
    Electronic Resource
    Comparison of processes regulating zooplankton assemblages in new freshwater pools (1998)
    Springer
    Hydrobiologia 287-388 (1998), S. 207-214 
    Details
    ISSN: 1573-5117
    Keywords: zooplankton ; rotifers ; colonization history ; disturbance ; nutrient enrichment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We compared the relative importance of colonization history to other known regulators of freshwater zooplankton assemblages (i.e. disturbance and nutrient enrichment) during this six-month study of initial colonization in artificial freshwater pools. We experimentally manipulated 16 small (1.5 m diameter) pools for permanence (permanent vs. temporary) and resource availability (± nitrogen & phosphorus). Nitrogen and phosphorus were added to high resource level pools in concentrations typical of eutrophic waters, while low resource level pools did not receive added nutrients. Permanent pools were maintained with added tap water and temporary pools dried out naturally for one month. Zooplankton colonization was limited to only 10 rotifers (species of Brachionus, Cephalodella, Lecane, Lepadella, Rotaria, and Trichocerca) and 2 crustaceans. Treatments significantly affected physical-chemical variables, colonization curves (species richness through time), and mean cumulative species number. Results indicate that local conditions (habitat permanence and resource availability) had the greatest effect on zooplankton species richness. However, low species diversity and little treatment effect on species relative abundance patterns suggest that colonization history (dispersal) was also important. Therefore, colonization history and local conditions were jointly responsible for structuring zooplankton assemblages in this study. Colonization history may have lasting effects on zooplankton composition in older, natural systems as well, but may be overlooked at some scales of measurement.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1017093810178
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  • 8
    Electronic Resource
    Electronic Resource
    Comparison of processes regulating zooplankton assemblages in new freshwater pools (1998)
    Springer
    Hydrobiologia 387-388 (1998), S. 207-214 
    Details
    ISSN: 1573-5117
    Keywords: zooplankton ; rotifers ; colonization history ; disturbance ; nutrient enrichment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We compared the relative importance of colonization history to other known regulators of freshwater zooplankton assemblages (i.e. disturbance and nutrient enrichment) during this six-month study of initial colonization in artificial freshwater pools. We experimentally manipulated 16 small (1.5 m diameter) pools for permanence (permanent vs. temporary) and resource availability (± nitrogen & phosphorus). Nitrogen and phosphorus were added to high resource level pools in concentrations typical of eutrophic waters, while low resource level pools did not receive added nutrients. Permanent pools were maintained with added tap water and temporary pools dried out naturally for one month. Zooplankton colonization was limited to only 10 rotifers (species of Brachionus, Cephalodella, Lecane, Lepadella, Rotaria, and Trichocerca) and 2 crustaceans. Treatments significantly affected physical-chemical variables, colonization curves (species richness through time), and mean cumulative species number. Results indicate that local conditions (habitat permanence and resource availability) had the greatest effect on zooplankton species richness. However, low species diversity and little treatment effect on species relative abundance patterns suggest that colonization history (dispersal) was also important. Therefore, colonization history and local conditions were jointly responsible for structuring zooplankton assemblages in this study. Colonization history may have lasting effects on zooplankton composition in older, natural systems as well, but may be overlooked at some scales of measurement.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1017093810178
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    Paper (German National Licenses)
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  • 9
    Electronic Resource
    Electronic Resource
    Zooplankton may not disperse readily in wind, rain, or waterfowl (1998)
    Springer
    Hydrobiologia 387-388 (1998), S. 15-21 
    Details
    ISSN: 1573-5117
    Keywords: Rotifera ; zooplankton ; dispersal ; colonization ; wind ; rain ; waterfowl
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Zooplankton, and especially rotifers, have long been thought to be readily dispersed by wind, rain and animals (especially waterfowl). Given that premise, local processes (tolerance to abiotic conditions, biotic interactions) have been the main focus of ecological studies. We tested the premise of high dispersal rates by incubating particulates collected with windsocks and rain samplers at two sites over 1 year. The sites were 80 km apart and differed in proximity to water and surrounding terrain. We also incubated fecal material of wild ducks. Pond sediments were identically incubated as a test of incubation method. Only bdelloid rotifers were collected in wind samples, and only four rotifer species were collected in rain samples: Lecane leontina, Lecane closterocerca, Keratella cochlearis, and a bdelloid. No metazoans were found in incubated duck feces, yet incubated pond sediments yielded 11 rotifer, one copepod, four cladoceran, and three ostracod species. Our results do not support the premise of readily dispersed zooplankton. If zooplankton dispersal is infrequent and limited to few species, a series of other questions should be addressed on processes regulating zooplankton population dynamics and community composition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1017080029317
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    Paper (German National Licenses)
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  • 10
    Electronic Resource
    Electronic Resource
    Reproductive systems of the north indian langur (Presbytis entellus entellus Dufresne) (1971)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 135 (1971), S. 99-129 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The gross anatomy and histology of the gonads and accessory sex organs are described for male and female Presbytis e. entellus. The langur differs from other catarrhine monkeys in certain specialised characters. The “sexual skin” is not comparable to the true sexual skin of the Cercopithecinae which exhibits cyclical change during the various phases of reproduction; it is nevertheless fully developed in the adult male and serves as one of the secondary sexual characters.Certain aspects of the reproductive system strikingly resemble those of man. The combined testicular weight (0.07% body weight) is similar to the human (0.08%), and the male has ampullary glands. The cervical canal is straight like that of a baboon or man. The corpus luteum (except in the lactating female) is a hollow glandular structure. Extensive hemorrhage which always accompanies ovulation in the langur, does not appear to be a common phenomenon in any other catarrhine for which ovulation and the development of corpus luteum have been studied. The hemorrhagic remains are retained for a long time in the ovulated follicle.The ovary is characteristically large and averages 0.74 gm without corpus luteum and 1.57 gm with corpus luteum, a feature never reported in any other catarrhine monkeys. The pre-ovulatory follicle may attain a size of 14 × 14 mm.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051350107
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